Old panaramic amp, reverb and tremolo issues

[alchemy]

Finally got around to getting this old amp up and running. Sounds great, but a coup[le issues...
Firstly, when turning the reverb pot, as i get about halfway up the signal starts to get attenuated. The output of the amp gets quieter. It does this whether or not the reverb is engaged. Ideas?

Second, the tremolo only seems to want to work in a very narrow range of both the speed and intensity controls. I have checked both pots for resistance while turning and they both have a smooth taper. Ideas? Actually, if anyone could point me towards a good primer on tremolo troubleshooting and operation, I would be most appreciative....